Health officials tracking measles and mumps outbreaks in Ohio are urging residents to stay up-to-date on immunizations to prevent illnesses from spreading.

The Department of Health says the spread of such diseases can accelerate when people gather in large groups, such as at picnics, camps, fairs and other common warm-weather activities.

Health agencies have confirmed 328 mumps cases in central Ohio, and 196 of those are linked to Ohio State University. Officials say the origin of the outbreak might never be known.

A measles outbreak is being tracked a bit further to the northeast in a six-county area. Twenty-nine of the 42 confirmed cases are in Knox County. Officials say that outbreak began with unvaccinated travelers who visited the Philippines, which has had a measles epidemic.